[PATCH 2/3] ARM: kprobes: Disallow instructions with PC and register specified shift
Jon Medhurst
tixy at linaro.org
Tue Mar 11 12:54:53 EDT 2014
ARM data processing instructions which have a register specified shift
are defined as UNPREDICTABLE if PC is used for any register, not just
the shift value as the code was previous assuming. This issue manifests
on A15 devices as either test case failures or undefined instructions
aborts.
Reported-by: David Long <dave.long at linaro.org>
Signed-off-by: Jon Medhurst <tixy at linaro.org>
---
arch/arm/kernel/kprobes-test-arm.c | 25 +++++++++++++------------
arch/arm/kernel/probes-arm.c | 6 +++---
2 files changed, 16 insertions(+), 15 deletions(-)
diff --git a/arch/arm/kernel/kprobes-test-arm.c b/arch/arm/kernel/kprobes-test-arm.c
index 87839de..8a7428b 100644
--- a/arch/arm/kernel/kprobes-test-arm.c
+++ b/arch/arm/kernel/kprobes-test-arm.c
@@ -73,12 +73,9 @@ void kprobe_arm_test_cases(void)
TEST_RRR( op "lt" s " r11, r",11,VAL1,", r",14,N(val),", asr r",7, 6,"")\
TEST_RR( op "gt" s " r12, r13" ", r",14,val, ", ror r",14,7,"")\
TEST_RR( op "le" s " r14, r",0, val, ", r13" ", lsl r",14,8,"")\
- TEST_RR( op s " r12, pc" ", r",14,val, ", ror r",14,7,"")\
- TEST_RR( op s " r14, r",0, val, ", pc" ", lsl r",14,8,"")\
TEST_R( op "eq" s " r0, r",11,VAL1,", #0xf5") \
TEST_R( op "ne" s " r11, r",0, VAL1,", #0xf5000000") \
- TEST_R( op s " r7, r",8, VAL2,", #0x000af000") \
- TEST( op s " r4, pc" ", #0x00005a00")
+ TEST_R( op s " r7, r",8, VAL2,", #0x000af000")
#define DATA_PROCESSING_DNM(op,val) \
_DATA_PROCESSING_DNM(op,"",val) \
@@ -102,8 +99,6 @@ void kprobe_arm_test_cases(void)
TEST_RRR( op "ge r",11,VAL1,", r",14,N(val),", asr r",7, 6,"") \
TEST_RR( op "le r13" ", r",14,val, ", ror r",14,7,"") \
TEST_RR( op "gt r",0, val, ", r13" ", lsl r",14,8,"") \
- TEST_RR( op " pc" ", r",14,val, ", ror r",14,7,"") \
- TEST_RR( op " r",0, val, ", pc" ", lsl r",14,8,"") \
TEST_R( op "eq r",11,VAL1,", #0xf5") \
TEST_R( op "ne r",0, VAL1,", #0xf5000000") \
TEST_R( op " r",8, VAL2,", #0x000af000")
@@ -124,7 +119,6 @@ void kprobe_arm_test_cases(void)
TEST_RR( op "ge" s " r11, r",11,N(val),", asr r",7, 6,"") \
TEST_RR( op "lt" s " r12, r",11,val, ", ror r",14,7,"") \
TEST_R( op "gt" s " r14, r13" ", lsl r",14,8,"") \
- TEST_R( op "le" s " r14, pc" ", lsl r",14,8,"") \
TEST( op "eq" s " r0, #0xf5") \
TEST( op "ne" s " r11, #0xf5000000") \
TEST( op s " r7, #0x000af000") \
@@ -158,12 +152,19 @@ void kprobe_arm_test_cases(void)
TEST_SUPPORTED("cmp pc, #0x1000");
TEST_SUPPORTED("cmp sp, #0x1000");
- /* Data-processing with PC as shift*/
+ /* Data-processing with PC and a shift count in a register */
TEST_UNSUPPORTED(".word 0xe15c0f1e @ cmp r12, r14, asl pc")
TEST_UNSUPPORTED(".word 0xe1a0cf1e @ mov r12, r14, asl pc")
TEST_UNSUPPORTED(".word 0xe08caf1e @ add r10, r12, r14, asl pc")
-
- /* Data-processing with PC as shift*/
+ TEST_UNSUPPORTED(".word 0xe151021f @ cmp r1, pc, lsl r2")
+ TEST_UNSUPPORTED(".word 0xe17f0211 @ cmn pc, r1, lsl r2")
+ TEST_UNSUPPORTED(".word 0xe1a0121f @ mov r1, pc, lsl r2")
+ TEST_UNSUPPORTED(".word 0xe1a0f211 @ mov pc, r1, lsl r2")
+ TEST_UNSUPPORTED(".word 0xe042131f @ sub r1, r2, pc, lsl r3")
+ TEST_UNSUPPORTED(".word 0xe1cf1312 @ bic r1, pc, r2, lsl r3")
+ TEST_UNSUPPORTED(".word 0xe081f312 @ add pc, r1, r2, lsl r3")
+
+ /* Data-processing with PC as a target a status registers updated */
TEST_UNSUPPORTED("movs pc, r1")
TEST_UNSUPPORTED("movs pc, r1, lsl r2")
TEST_UNSUPPORTED("movs pc, #0x10000")
@@ -186,14 +187,14 @@ void kprobe_arm_test_cases(void)
TEST_BF_R ("add pc, pc, r",14,2f-1f-8,"")
TEST_BF_R ("add pc, r",14,2f-1f-8,", pc")
TEST_BF_R ("mov pc, r",0,2f,"")
- TEST_BF_RR("mov pc, r",0,2f,", asl r",1,0,"")
+ TEST_BF_R ("add pc, pc, r",14,(2f-1f-8)*2,", asr #1")
TEST_BB( "sub pc, pc, #1b-2b+8")
#if __LINUX_ARM_ARCH__ == 6 && !defined(CONFIG_CPU_V7)
TEST_BB( "sub pc, pc, #1b-2b+8-2") /* UNPREDICTABLE before and after ARMv6 */
#endif
TEST_BB_R( "sub pc, pc, r",14, 1f-2f+8,"")
TEST_BB_R( "rsb pc, r",14,1f-2f+8,", pc")
- TEST_RR( "add pc, pc, r",10,-2,", asl r",11,1,"")
+ TEST_R( "add pc, pc, r",10,-2,", asl #1")
#ifdef CONFIG_THUMB2_KERNEL
TEST_ARM_TO_THUMB_INTERWORK_R("add pc, pc, r",0,3f-1f-8+1,"")
TEST_ARM_TO_THUMB_INTERWORK_R("sub pc, r",0,3f+8+1,", #8")
diff --git a/arch/arm/kernel/probes-arm.c b/arch/arm/kernel/probes-arm.c
index 51a13a0..8eaef81 100644
--- a/arch/arm/kernel/probes-arm.c
+++ b/arch/arm/kernel/probes-arm.c
@@ -341,12 +341,12 @@ static const union decode_item arm_cccc_000x_table[] = {
/* CMP (reg-shift reg) cccc 0001 0101 xxxx xxxx xxxx 0xx1 xxxx */
/* CMN (reg-shift reg) cccc 0001 0111 xxxx xxxx xxxx 0xx1 xxxx */
DECODE_EMULATEX (0x0f900090, 0x01100010, PROBES_DATA_PROCESSING_REG,
- REGS(ANY, 0, NOPC, 0, ANY)),
+ REGS(NOPC, 0, NOPC, 0, NOPC)),
/* MOV (reg-shift reg) cccc 0001 101x xxxx xxxx xxxx 0xx1 xxxx */
/* MVN (reg-shift reg) cccc 0001 111x xxxx xxxx xxxx 0xx1 xxxx */
DECODE_EMULATEX (0x0fa00090, 0x01a00010, PROBES_DATA_PROCESSING_REG,
- REGS(0, ANY, NOPC, 0, ANY)),
+ REGS(0, NOPC, NOPC, 0, NOPC)),
/* AND (reg-shift reg) cccc 0000 000x xxxx xxxx xxxx 0xx1 xxxx */
/* EOR (reg-shift reg) cccc 0000 001x xxxx xxxx xxxx 0xx1 xxxx */
@@ -359,7 +359,7 @@ static const union decode_item arm_cccc_000x_table[] = {
/* ORR (reg-shift reg) cccc 0001 100x xxxx xxxx xxxx 0xx1 xxxx */
/* BIC (reg-shift reg) cccc 0001 110x xxxx xxxx xxxx 0xx1 xxxx */
DECODE_EMULATEX (0x0e000090, 0x00000010, PROBES_DATA_PROCESSING_REG,
- REGS(ANY, ANY, NOPC, 0, ANY)),
+ REGS(NOPC, NOPC, NOPC, 0, NOPC)),
DECODE_END
};
--
1.7.10.4
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